1. Field of the Invention
The present invention relates to a cooling module. In particular, the invention relates to a cooling module for use with a DLP projector.
2. Descriptions of the Related Art
Many consumers have chosen to use projectors as their display equipments in offices, homes, and conference rooms. There are two types of conventional projectors: liquid crystal display (LCD) projectors or digital light processing (DLP) projectors. Because DLP projectors apply digital projecting and displaying technologies, they are extremely welcome in the display market.
DLP projectors employ DMD (digital micromirror device) modules as their core technology. The DMD module is composed of a micro mirrors array, fabricated by semiconductor manufacturing processes. Each mirror is a display pixel. When light is projected onto the DMD module from a light source, the micro mirrors of the DMD immediately reflect the light towards the projection lens for image formations according to its image signals.
However, light possesses energy itself When light hits the DMD module, heat is subsequently generated. Effective cooling for the DMD module quickly turns into an important issue. Conventionally, heat conduction pad, which also work with fans for cooling, have been attached to the DMD modules. A well known DLP projector 10 is shown in FIG. 1. The light that is generated from a light source 11 is partially projected onto a DMD module 15 and through an optical engine 13 for image formations. In general, the DMD module 15 is adjacently in contact with the heat conduction pad 16 to prevent heat accumulation thereon. At least one fan 12 is disposed inside the DLP projector 10 for generating cooling airflows. These cooling airflows can be utilized to cool the pad 16 on the DMD module 15 or even other components in the system as well.
Because the watts and efficiency of the light source 11 have progressively increased in response to the increased use of high-lumen projectors, energy (e.g. light and heat) accumulated on the DMD module 15 has also increased. The use of a larger pad or having greater airflows does not sufficiently cool the DMD module 15. The size of the pad 16 and the rotational speed of the fan 12 have to be controlled according to the size of the product and the noise level. Consequently, it has been increasingly difficult to cool the DMD module 15. Overheats may shorten the DMD module 15 life or even terminate the operation of the projection apparatus early.
Besides, venting apertures 191 are usually disposed on the housing 19 to promote cooling airflows for the DLP projector 10. These venting apertures 191 provide a channel between the interior of the system and the surroundings for heat exchange. With respect to this kind of heat generating system, venting apertures 191 are essential in design. However, due to the light source 11 with high luminance in the projector, partial light which is generated from the light source 11 and is not guided into the optical engine for the DMD module 15 may leak out from the housing 19 and through the venting apertures 191. As a result, this light not only causes discomfort in the user's eye, but also causes light pollution in the projection environment, affecting the projection performance. Moreover, the high temperature may damage the housing 19 and increase the risk of injury to users. Conventionally, a light shelter 17 is usually disposed adjacent to the venting apertures 191 to prevent light from leakage or the user from directly seeing through the light source 11 from the exterior of the system. To block these light leakages, the light shelter 17 disposed on the venting apertures 191 raises airflow resistance instead, which does not benefit for cooling the interior of the DLP projector 10. Furthermore, the increase in airflow resistance may also raise system noises.
Given the above, a novel cooling module that can shield light for use in a projection apparatus is needed in this field.